Method of lining metal articles



14, 1961 M. D. WOODRUFF ETAL- 2,971,225

METHOD OF LINING METAL ARTICLES Filed Sept. 18. 1958 INVENTO Ilnumc: D-Vocoflu BY Cmuuss vJlrrn.

United States Patent METHOD OF LINING METAL ARTICLES Maurice D. Woodrulf and Charles Victor Appel, Springfield, Ohio, assignors to The Bauer Brothers Company, Springfield, Ohio, a corporation of Ohio Filed Sept. 18, 1958, Ser. No. 761,781

5 Claims. (CI- 18-59) This invention relates to the lining of metal articles and more particularly to a method for lining cast or otherwise formed metal articles with a plastic coating. The method may used in connection with articles having both regular and irregular shaped interiors and will provide a plastic coating of uniform thickness upon all of the interior surfaces of the articles.

This application is a continuation-in-part of our 00- pending application Serial No. 500,085, filed April 8, 1955, and entitled Apparatus and Method of Lining Metal Articles, now abandoned.

The object of the invention is to simplify the methods of lining cast articles with a plastic or other similar material, whereby such lined castings may not only be economically manufactured but will be more efiicient and satisfactory in use and the lining, its means and method of application, adaptable to a wide variety of articles.

A further object of the invention is to provide a method of molding a plastic or resinous lining upon the interior surfaces of preformed articles.

A further object of the invention is to provide an improved method for lining preformed articles employing a mold which may be easily inserted in and withdrawn from the article to be lined.

A further object of the invention is to provide, where necessary, an improved method for lining preformed articles employing a multi-part mold which may be placed in various portions of the interior of the article to be line together with a means for securing said mold to the article to be lined.

A further object of the invention is to provide a method of introducing a liquid plastic or resin to the space intermediate the mold and the interior surfaces of the article to be lined in such a way as to evacuate all air therefrom.

A further object of the invention is to provide a method whereby the lining which has been introduced intermediate the mold and the article to be lined may be gelled and set to the form desired.

A further object of the invention is to provide method of accommodating the expansion of the plastic fining material during the gelling and setting operation.

A further object of the invention is to provide a novel method of lining preformed articles employing a mold which may be easily secured to the article to be lined and which after initial gelling and setting may be easily removed therefrom.

A further object of the invention is to provide a method for lining cast articles possessing the advantageous features, the inherent meritorious characteristics and the mode of use herein mentioned.

With the above primary and other incidental objects in view as will more fully appear in the specification, the invention intended to be protected by Letters Patent consists of the features of construction, the parts and combinations thereof, and the mode of operation as hereinafter described or illustrated in the accompanying drawinns, or their equivalents.

2,911,225 Patented Feb. 14, 1961 Referring to the accompanying drawing wherein is found one, but obviously not necessarily the only form embodiment of the invention,

Fig. l is a sectional view somewhat diagrammatic, showing an article to be lined with the mold in place therein;

Fig. 2 is a top view thereof;

Fig. 3 is a bottom view of a portion of Fig. l; and

Fig. 4 is a transverse sectional view taken substantially along the line 44 of Fig. 1.

Like parts are indicated by similar characters of reference throughout the several views.

Referring to the drawings there is shown in Fig. 1 a sectional view through a cast article of rather complicated or intricate design, which is to be lined with a plastic or resin coating. Such article 1 is hollow and of generally circular form. It has projecting from the top thereof an annular machined mounting flange 2 of somewhat less diameter than the body of the article 1. Also extending laterally therefrom is a machined mounting flange 3 which is arranged in tangential relation to the inner chamber of the main body portion 1. The lower portion of the body 1 has circular machined mounting flange therearound by means of which the body 1 is connected to associated equipment. By the same token the flanges 2 and 3 provide means for connecting the body 1 to other associated equipment.

As will be readily appreciated, an article such as this having offset and irregular interior surfaces would be quite difiicult to line, particularly when the article is of cast construction and the interior surfaces thereof are not subsequently machined prior to the lining operation. Only the flanges and flange counterbores of the casting are machined and by molding the lining a very accurate interior surface is produced even though the thickness of the coating may vary from area to area. The normal procedure in attempting to line or coat articles of this type with plastic has been to dip the article in a tank of the coating material. After dipping, the article is then withdrawn and hung over the tank to drip dry. After the excess coating material has dripped therefrom the coated article is then either air gelled and set or placed in an oven for gelling and setting. Such process, however, is impossible with articles having an interior contour of the shape shown herein wherein the surfaces are relatively rough and unmachined and are offset relatively to one another. By molding, square corners are produced so that when one part is attached to another the interior surface of the two parts is continuous. Furthermore, by

molding the lining, the material is applied to only the interior surfaces, whereas a clipping process would coat all surfaces to the same extent. The exterior surfaces of such articles do not require protection of the type provided or required on the interior surfaces. For these reasons the dipping process heretofore normally used could not satisfactorily be used in lining articles of the present WW- Thee present method and apparatus has been designed to overcome the difiiculties heretofore encountered in the coating of articles of this type and a means is hereby provided whereby articles of the general type shown herein may be satisfactorily coated to a uniform surface over the entire surface upon which a coating is desired.

Such uniform coating is obtained by use of a mold whereby the finished product has in effect had-a molded lining or coating applied to the interior surfaces thereof.

For the article shown, the mold consists of three parts,

one for the main cavity in the article 1, a second for the cavity in the upstanding mounting flange 2, and a third for the cavity in the lateral mounting flange 3.

The first of these mold parts comprises a base plate 5 to which is secured an upstanding mandrel 6. The mandrel 6 may be made integrally with the base plate or may be formed separately therefrom and subsequently fixedly secured thereto. The dimensions of the mandrel 6 are such that when concentrically placed within the body 1 the outer surface of mandrel 6 represents the proper desired dimension for the inner surface of the body 1 with the coating applied thereto. The base plate 5 is placed upon a table or other supporting surface and the body 1 located thereon. The body and the base plate 5 with its integral mandrel 6 are then secured to one another by means of a series of bolts 6 which pass through the mounting flange 4 on the body 1 and the base plate 5. The plate 5 and the mandrel 6 are concentrically located relative to the body 1 by a machined counterbore in flange 4 which establishes the proper concentric rela tionship between the parts when secured to the body 1 in the manner shown.

The second mold part for use in the upstanding mounting flange 2 may be a solid piece or it may be fabricated from a plurality of pieces. It resembles in principle the main mold portion in that it has a plate area and projecting body or mandrel. Again the dimensions of the mold part 7 are so proportioned as to provide, when concentrically located within the machined counterbore of flange 2, the desired interior dimension for the body adjacent flange 2.

In this particular example it is not desired to have the lining material extend across the opening into the mounting flange 2 and the mold part 7 is therefore so designed as to firmly contact the upper surface of the mandrel 6 when properly placed in position. The mold part 7 is then, similarly to the mandrel 6, secured in the body by means of bolts 8 passing through a flange on the mold parts 7 and the mounting flange 2 of the body 1.

Mold part 9 inserted within the laterally projecting mounting flange 3 is similar to the mold part 7 in construction, it being so proportioned as to fit within the mounting flange 3 with the necessary desired clearance. It is likewise retained in position by means of a series of bolts 10 which extend through the mold part 9 and the mounting flange 3 to thereby fixedly maintain the mold 9 in properly adjusted position.

In this particular application the mold part 9 is designed and shaped as to wrap around a portion of the central mold-part 6. (More clearly shown in Fig. 4.) Such formation of the mold part 9 is necessitated by the tangential location of the mounting flange 3 and its associated conduit leading into the central chamber of the body 1 at a tangent thereto. Again, like the mold part 7, the mold part 9 where it fits against the main mold part 6 is so designed as to have a close fit therewith so as to prevent entrance of lining material therebetween. In the example used herein, it is desired to line or coat only the interior surfaces of the chamber, within the body 1 and the surfaces of the mounting flanges 2 and 3, and their interconnecting conduits.

It will be noted in this example that at all openings, i.e. at the flange 4, the flange 2 and the flange 3, the lining material is formed over a portion of the horizontal surface of the respective flanges. In the case of the flanges 2 and 4 on the body 1 this is accomplished by relieving the surface of the flanges so as to provide intermediate the body and the mounting plates for the mold portions an opening of the desired thickness. In the case of the mounting flange 3 the lining material is placed over the face of the flange 3 by means of a recess machined into the outer plate portion of the mold 9.

When finished these portions of the lining form a gasket against which the adjoining unit seats when placed thereon and secured to the housing 1 by means of bolts passed through the various mounting flanges.

Before using, the exterior surfaces of the mold parts 6, 7 and 9 are impregnated with whiting or other material which renders'these surfaces non-adhesive to the particular material being used as the lining. Without such .would tend to adhere to the interior mold or mandrels and it would be impossible to withdraw the mold without defacing and marring the molded lining.

In order to secure a non-porous lining it is necessary that the material from which the lining is to be made be as free of air as possible. It is also necessary that the cavity in which the material is to be placed be evacuated and that no air be trapped intermediate the mold portions and the body 1.

The plastic or other material to be used in forming the lining is maintained in supply tank 11 wherein reasonable efforts are made to maintain the trapped air within the material at a minimum. The material, for example a liquid vinyl plastisol, is then pumped from the supply tank 11 by means of pump 12 to a header or distributor 13.

A preferred vinyl plastisol is compounded of the following ingredients:

parts vinyl chloride polymer 30-75 parts plasticizer (blend of phthalates and phosphates) 2-5 parts heat stabilizer 2-5 parts pigment Arranged in the base plate 5 of the main mandrel 6 is a circular series of openings 14 arranged in approximate alignment with the location of the lining intermediate of the body 1 and the mandrel 6. Each of the openings 14 are connected with the distributor or header 13 by means of a series of radiating conduits 15, each conduit having a valve 16 therein. The lining material is thereby forced into the space intermediate the body 1 and the mandrel 6 under pressure created by the pump 12, and the lining material gradually fills the cavity within the assembled parts.

So that any air trapped within the assembled parts may also escape, a circular series of vents 17 are arranged in the upper mold part 7, such vents again being in approximate alignment with the upper end of the mold cavity, i.e.

the space intermediate the mold 7 and the flange 2 on the body 1. Thus, any air trapped within the mold cavity is gradually forced therefrom as the lining material flows upwardly through the cavity. The mold part 9 likewise has an air vent 18 therein so as to vent any air which might be trapped in the mold cavity within the tangential mounting flange 3.

As soon as the lining material has completely filled the mold cavity it will bubble from the vent holes 17 and 18. Such escape of the lining material indicates that the cavity is then completely filled and the pump 12 is thereupon stopped. The valves 16 are then closed and the lines 15 disconnected from the plate 5. The vents 17 and 18 are likewise closed by the insertion of plugs therein.

Prior to the insertion of the molds 6, 7 and 9 and the introduction of the lining material thereon the part 1 to be lined is sandblasted and cleaned. It is then immersed in a primer which is permitted to air dry thereon. The primer, generally a mixture of vinyl and phenolic resin is used to condition the body 1 for the reception and retention of the lining material.

If it is desired that the outside of the body 1 be provided with a coating similar to the inside but not molded, the entire unit may be sprayed with the coating material.

After filling of the cavity intermediate of the body 1 and the mold parts 6, 7 and 9 with the lining material and the spraying of the outside of the body 1, if desired, the entire unit is then ready for the gelling and setting operation which is preferably done in an oven. Upon closure of the vents 17, 18 and closure of the valves 16 and removal of the supply lines 15 the unit is introduced into a preheated oven, the temperature of which is approximately 380' F. This temperature is not overly critical and may be varied somewhat both above and below the particular temperature noted. It has, however, been found that a temperature approximately 380 F. is quite satisfactory. After introduction of the unit into the pre-.

heated oven the temperature thereof is then rapidly increased to approximately 535 F. Again this exact temperature is not critical but the temperature should be relatively close to this figure.

By rapidly increasing the temperature in the oven the maximum heat input to the article 1 is accomplished at this time and rapidly. The high temperature is main tained in the oven for approximately 30 to 40 minutes so as to thoroughly heat the article and then the oven is reset for the lower temperature in the neighborhood of 380 F. The gelling and setting then continues at the lower temperature for a period of approximately 50 to 60 minutes, making a total time of gelling and setting in the oven approximately 1% hours.

The rapid input of heat to the article provides a better adhesion of the vinyl lining material to the metal and results in a more satisfactory product than if the temperature were slowly increased during the gelling and setting period.

During gelling and setting the lining material which has been injected intermediate the mold parts and the body 1 has a tendency to expand. To accommodate and control such expansion one or more of the mold parts, in this instance the mold part 7, is provided with a plurality of spaced relief openings 19 intermediate the flange 2 and the mold part 7. As the lining material expands it can therefore flow outwardly through the plurality of relief openings.

After completion of the gelling and setting period in the oven the units are then withdrawn from the oven and placed in a cooling tunnel where air is drawn over the units by a fan. The volume of air drawn over the units in the cooling tunnel is such that the units will cool to approximate room temperature in about 45 minutes.

After cooling of the gelled and set units the mold parts are then removed from the body 1 and the gates are trimmed off. Such gates are formed at the inlet openings 14, the vent openings 17 and 18, and possibly at the relief openings 19.

At this point the lining which has been molded into the body 1 has a rather rough interior. Apparently part of the lining material remains in contact with the mandrel through the gelling and setting operation while other parts of the lining pull slightly away from the mandrel. It has been found from experience that this condition is desirable, since it indicates a maximum gelling and setting of the lining material.

The lined body is then placed on a metal plate in spaced relation therewith and a second metal plate is laid over the top flange 2 thereof, again in spaced relation with the flange. It is necessary that the metal plates be held in spaced relation with body 1 so that the lining material will at no time contact the two metal plates. The unit is then again placed in the oven which has been preheated to approximately 370 F., the metal plates protecting the coating from the direct heat of the oven. The unit, so protected, is left in the oven for a further period of approximately 45 minutes, which raises the temperature of the lining material to a point where the surface roughness completely disappears. This reheating of the gelled and set lining softens the lining material sufficiently that it can reform and, due to the elastic memory of the material, it reforms to the original shape in which it was solidified during the molding and initial gelling and setting operation. It has also been found that the additional gelling and setting, which takes place during this further period in the oven, gives a tougher and more durable lining to the article than would otherwise be achieved.

Following the second period in the oven the unit is then placed again in the cooling tunnel and brought down to approximately atmospheric temperature. Following this last cooling the part is ground to remove any remaining flash and the lined part is then ready for use.

The lining on the body 1, formed in accordance with this disclosure, is of desired dimensions throughout and the surfaces are smooth and in proper relation one to another notwithstanding the somewhat complicated and intiiicrztg shape and contour of the body 1 which is to From the above description it will be apparent that there is thus provided a device of the character described possessing the particular features of advantage before enumerated as desirable, but which obviously is susceptible of modification in its form, proportions, detail construction and arrangement of parts without departing from the principle involved or sacrificing any of its advantages.

While in order to comply with the statute the invention has been described in language more or less specific as to structural features, it is to be understood that the invention is not limited to the specific features shown, but that the means and construction herein disclosed comprise but one of several modes of putting the invention into effect, and the invention is therefore claimed in any of its forms or modifications within the legitimate and valid scope of the appended claims.

Having thus described our invention, we claim:

1. A method of lining preformed articles with a plastic material having the property of elastic memory consisting of the steps of introducing a mold in the preformed article spaced from said preformed article thereby providing a cavity of predetermined thickness in conjunction with the surface of said preformed article to be lined, introducing liquified heat settable plastic material having the property of elastic memory in the cavity between the mold and the inner surface of the preformed article, forcing entrapped air from the cavity in the process, introducing the unit so provided into a preheated oven, rapidly increasing the oven temperature to a substantial degree to rapidly and thoroughly heat the unit, reducing the oven temperature substantially to that at which the article was introduced, cooling the unit to room temperature, removing the mold and reheating the preformed article to approximately the temperature of the oven as initially provided and again cooling the article to room temperature, providing a complete adhesion of a smooth plastic lining to the preformed article.

2. A method of lining preformed articles with a plastic material having the property of elastic memory, consisting of the steps of introducing a mold in the preformed article providing a closed cavity of predetermined thickness in conjunction with the surface to be lined, filling the cavity so made with a heat settable plastic material and forcing entrapped air from the cavity, introducing the unit into an oven preheated to approximately 380 F., rapidly increasing the oven temperature to approximately 535 F. and maintaining this temperature for approximately 30 minutes, reducing the oven temperature to approximately 380 and maintaining this temperature for approximately 60 minutes, withdrawing the article from the oven and cooling to atmospheric temperature, removing said mold and again introducing the article into the oven at approximately 370 F. for a predetermined period of time to reform the plastic material lining the article so that surface roughness completely disappears to thereby form a tough and durable lining to said article, withdrawing the lined article from the oven and cooling to atmospheric temperature.

3. A method of coating the interior surface of preformed articles with plastic having the property of elastic memory wherein a removable mold assembly is placed in spaced relation to the interior surface to provide a cavity therebctween corresponding in thickness to the thickness of the lining to be coated on the article, consisting of the steps of introducing heat settable plastic material under pressure in the cavity intermediate the mold and the interior surface of the preformed article to be coated, forcing entrapped air from said cavity, sealing the cavity, subjecting the unit so formed to a given temperature and rapidly raising the temperature for a predetermined period, thereafter cooling the unit to room temperature, removing the mold from the article and again subjecting the preformed article and unconfined plastic coating therefor to said temperature to which the unit was initially subjected for a predetermined period to reform the lining to a smooth condition and render it tough and durable and again cooling the article to room temperature.

4. A method of coating the interior surfaces of preformed articles, comprising the steps of placing a removable mold in spaced relation to the interior surfaces of the article to be coated, a cavity being provided therebetween, introducing heat settable plastic material in a flowable form into the cavity, subjecting the assembly comprising said article, said mold and said plastic material to a rapid increase in temperature to an appropriate level, the plastic material having a character causing it to gel and set upon said interior surfaces at the increased temperature, cooling said assembly and thereafter removing the mold, the surface of the gelled and set plastic ma-' terial being in this process deformed, and reheating the plastic to the level of elastic deformation enabling the inherent elastic memory of the plastic material to reform to its original shape the deformed surface of such material.

5. A method of coating the interior surface of a preformed article, comprising the steps of placing a removable mold in spaced relation to the interior surfaces of the article to be coated, a cavity being provided therebetween, introducing heat settable plastic material. having the property of elastic memory, in a fiowable form into the cavity, subjecting said article, mold, and plastic material to a rapid increase in temperature to an appropriate level and inducing a gelling and setting of the plastic material on the interior surfaces of the article thereby, cooling the article, mold, and plastic, thereafter removing the mold and reheating the article and plastic to the level of elastic deformation of the plastic enabling the inherent elastic memory of the plastic material to cause it to reform and effect atough, durable and smooth surface coating on the interior surface of the article, the reheating temperature being at'a lower level than the temperature at said appropriate level.

References Cited in the file of this patent UNITED STATES PATENTS 

